What is a Charge Cycle? Will charging too often spoil my battery?
Apple.com has the answer.
The long and short of it is, If you charge your battery 50% now, then you disconnect the charger, then you connect it back for 20%, disconnect, and you connnect it back for 30%, that adds up to 1 charge cycle (50%+20%+30%=100%).
Therefore, you need a full cycle, 0 to 100%, to constitute to 1 charge cycle.
As for charging too often, well, this is a personal thing. Right now, I’m using my MBP plugged in. So far, so good. Only complaints, the processor slowdown (probably to control the heat).